This invention relates to crosslinkable compositions comprising saccharide-siloxane copolymers and a crosslinking agent. The copolymers comprise a saccharide-derived polyhydroxyl-functional moiety covalently linked to an organosilicon backbone. The crosslinkable copolymers form a crosslinked network in the presence of reactive crosslinking agents which link the copolymers via the polyhydroxy-functionality of the saccharide components. The invention further relates to the crosslinked networks, cured coatings, and articles of manufacture comprised thereof.
Organosiloxanes comprising a saccharide component, and process for making them are known in the art. Saccharides comprising aldonolactones are particularly suitable for linking to amine-functional organosilicons. For example, U.S. Pat. No. 4,591,652 describes manufacturing polyhydroxyl silanes by reacting silanes having amine-terminated substituents with aldonic acid lactones. Japanese patent No. 62-68820 discloses organopolysiloxanes comprising saccharide residues made from aminosiloxanes and saccharide lactones. WO 94/29324 describes siloxanyl-modified compounds, methods for their preparation and applications as surface-active and surface-modifying agents, particularly in plant protection. It more particularly discloses surface-active or surface-modifying agents formed from epoxy-trisiloxane reaction products and saccharide lactones. WO 02/088456 describes amido-functional aminopolydiorganosiloxanes, a method for the production thereof, preparations comprising the amido-functional aminopolydiorganosiloxanes and applications in the textile industry. The amido-functional siloxanes are formed from reacting aminosiloxanes and saccharide lactones.
Other processes for covalently linking saccharide molecules and silicone-based compounds, including polydialkylsiloxanes, are also known. For example, U.S. Pat. No. 5,831,080 describes organosilicon compounds comprising glycoside radicals made by hydrosilylating allyl functional saccharide groups. U.S. Pat. No. 6,517,933 B1 describes a hybrid polymer material comprising a set of naturally occurring building blocks, which include saccharides, and a set of synthetic building blocks that include polysiloxanes. A number of potential linking chemistries are described. U.S. Patent Application Serial No. 20040082024 to Brandstadt et al. discloses ester linked saccharide-siloxanes and enzyme-catalyzed esterification processes. All of this referenced art describes saccharide-siloxane copolymers comprising polyhydroxy functionality that may be suitably employed in the present invention. The prior-cited art is fully incorporated herein by reference.
There is some technology directed to crosslinking of saccharides, and other polyhydroxylpolymers and to the materials comprised thereof. For instance, U.S. Pat. No. 6,132,822 discloses a high gloss coated sheet material made from a porous sheet and coating comprising a water dispersible crosslinkable polymer and a water dispersible film-forming polymer. '822 teaches polyhydroxyl polymers like poly(vinyl alcohol) as preferred crosslinkable polymers. The preferred crosslinking agents disclosed are glyoxal, epichlorohydrin, metal ions, fatty acid complexes of metal ions, and exposure to energy.
U.S. Pat. No. 5,252,233 describes a heat curable hydrophilic finish produced on cellulose-containing textiles used to impart durability to hydrophilic textiles. The finishing agent comprises: 1) an organo-modified silicone containing either hydroxy-terminal polyether groups or hydroxyl groups derived from 3,4-epoxycyclohexyl ethyl or 3-glycidyloxypropyl groups; 2) glyoxal; 3) glycol; and 4) a acidic catalyst.
U.S. Pat. No. 4,269,603 describes a process for imparting durable press properties to a textile fabric formed at least partly of cellulosic fibers using a finishing agent. The finishing agent comprises glyoxal, reactive silicone and a catalyst.
DE Patent No. 19918627 describes a novel polymer composition comprising water-soluble polymers, silicon oxide components, and titanate or zirconate crosslinkers. The water-soluble polymers are polysaccharides, proteins or cellulose derivatives. The silicone compounds are alkoxysilane hydrolysates. The hybrid polymers are proposed as carrier systems for the controlled release of drugs.
U.S. Patent Application Serial No. 2004 0091730 A1 describes a wood product made from sequentially treating wood with two solutions. The penetrating solution contains boric acid, a metallocene catalyst, a free radical initiator, a film forming polymer and adhesion promoter. The topcoat includes a film-forming polymer. The film-forming polymer is an acrylic or siloxane based polymer or copolymer. The metallocene catalyst contains tin or titanate.
Organosiloxane-based elastomers formed from crosslinking organosiloxane polymers are well known in the art and such materials have wide-ranging utility as coatings which confer desirable surface properties to the coated substrate, for example, enhanced resistance to wear, thermal stability, hydrophobicity and resistance to water, adhesion control and release, frictional control including anti-slip capability, and so on. Various fillers and other additives may be included within the elastomeric matrix to provide coatings with even more varied performance benefits. The mechanical, chemical and ionic characteristics of the crosslinked network matrix influences both the nature and amount of additives that may suitably be included. Compositions and cured coating compositions comprising crosslinked carbohydrates are known in the art. However, the present inventors are unaware of compositions and cured coating compositions comprising saccharide-siloxane copolymers crosslinked via the polyhydroxyl functionality of the saccharide. The networked matrix and cured coatings formed from these unique crosslinkable compositions would provide a blended property profile comprising attributes of both silicone and carbohydrate-based matrices which may support, retain and/or controllably release a variety of additives. Crosslinking via the saccharide component of the copolymer yields elastomers possessing a property profile making them desirable for particular applications.
Hence, there is a need in the art for crosslinkable compositions comprising saccharide-siloxane copolymers wherein the saccharide-siloxanes form a crosslinked network by linking between the hydroxyl functionalities possessed by the polyhydroxyl saccharide-derived backbone of the copolymers. There is also a need in the art for cured coating compositions comprised therefrom, which reflect the benefits and characteristics known to be imparted by coatings that comprise both silicone and carbohydrate components, as well as the unique properties which may be conferred by a cured matrix comprising a saccharide to saccharide linked network. There is a further need in the art for coatings that confer improved such benefits and characteristics to the coated substrate, and the improved substrates and articles comprising them.